If you're posting a request for installation help, please provide as much info about your system as possible. For example, for help regarding connecting a smart thermostat, please include details about your system including whether you have gas/electric, heat pump, number of heat stages, A/C condenser, etc.

Honeywell IAQ to Ecobee3, Variable Speed Air Handler, Heatpump, Electric Aux, etc.

Hi All,

I'm looking to replace my Honeywell IAQ (not prestige) with an Ecobee3. My system is a Trane 2.5t XL15i (4TWX5030B1), and the air handler is a 4TEE3F39A1 (variable speed fan) with a 10KW Aux heat electric strip. The IAQ also provides dehumidification via overcool.

Currently I have just the single IAQ thermostat, so it's only got 3 wires hooked up. Thankfully when my system was installed, they ran a full 10 wires between the air handler and the thermostat, just left most unhooked.

I understand I have to remove the EIM from the system, and wire the Ecobee3 directly to the air handler, but I'm not 100% sure how to do this. Obviously red and blue are easy, as are probably the other main wires, but I'm not clear on things like dehumidification, etc. I saw somewhere someone commenting about their air handler having an ACC+ terminal, but I'm not sure mine does.

Also, and this is key, I have the IAQ set to run the fan all the time to keep air circulating, but since the air handler is variable, the fan runs at a lower speed. Is this is IAQ that does this speed control, or is it the air handler? I would rather not lose this circulation or have the fan run at full blast all the time. =/

Any help would be greatly appreciated.

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